which is different from (REF ), since \(\varphi ^{a}\)  in (REF ) does not possess the component index \(A\) .
For more details about the equation of motion in (REF ), see Ref. [1]} for instance. Note that the wave function \(\varphi ^{a}\)  in (REF ) describes only a positive energy solution for the massive photon with spin one, and thus it cannot produce the massive antimass-photon aspects discussed in the Dirac type RQM for the massive photon with spin one.
